Fractional flow reserve-guided coronary bypass surgery: should surgeons use it?

Clinical Outcomes of Surgical Revascularization Strategies Guided by Quantitative Flow Ratio in Primary Noncoronary Cardiac Surgery

PURPOSE

Information regarding quantitative flow ratio (QFR) usage in coronary artery bypass grafting (CABG) is lacking. We compared the incidence of postoperative long-term adverse cardiovascular and cerebrovascular events after QFR-guided or coronary angiography-guided adult cardiac surgery with concurrent bypass surgery.

MATERIALS AND METHODS

This study included 432 patients who underwent cardiopulmonary bypass (CPB) at our institution with at least 1 angiographical coronary artery lesion (diameter stenosis: 30% to 90%) between January 2015 and January 2016. The QFR of each patient was calculated. Patients who only underwent intraoperative coronary revascularization following the principles of optimal revascularization strategy were assigned to group A. Patients with coronary lesions not meeting the above criteria were placed in group B.

RESULTS

The average number of distal anastomoses of patients with combined CABG in group B was similar to that in Group A (1.9±1.0 vs. 1.7±0.9; P =0.081). Group A had a shorter CPB duration (114.4±49.2 vs 135.8±55.2 minutes; P <0.001) and shorter aortic cross-clamping time (83.6±36.2 vs 101.1±40.6 minutes; P <0.001). The rates of perioperative mortality and major complications did not differ between groups. Long-term major adverse cardiovascular and cerebrovascular events (MACCEs) were less common in group A than in group B (14.7% vs 29.5%; P <0.001).

CONCLUSIONS

In primary noncoronary cardiac surgery, despite the similar average numbers of distal anastomoses, the group with target vessels treated using an optimal coronary revascularization strategy presented shorter CPB time and aortic cross-clamping time than the other group. Multivariate analyses also showed a lower incidence of long-term MACCEs.

The Impact of Fractional Flow Reserve on Clinical Outcomes after Coronary Artery Bypass Grafting: A Meta-analysis

Background

This meta-analysis was conducted to evaluate the effect of fractional flow reserve (FFR) on clinical outcomes after coronary artery bypass grafting (CABG).

Methods

Five online databases were searched for studies that (1) enrolled patients who underwent isolated CABG or CABG with aortic valve replacement and (2) demonstrated the effect of an FFR-guided strategy on major adverse cardiac events (MACE) after surgery based on a randomized controlled trial or adjusted analysis. MACE included cardiac death, acute myocardial infarction (MI), and repeated revascularization. The primary outcomes were all MACE outcomes and a composite of all-cause death and MI, and the secondary outcomes were the individual MACE outcomes. Publication bias was assessed using a funnel plot and the Egger test.

Results

Six articles (3 randomized and 3 non-randomized studies: n=1,027) were selected. MACE data were extracted from 4 studies. The pooled analyses showed that the risk of MACE was not significantly different between patients who underwent FFR-guided CABG and those who underwent angiography-guided CABG (hazard ratio [HR], 0.80; 95% CI, 0.57-1.12). However, the risk of the composite of death or MI was significantly lower in patients undergoing FFR-guided CABG (HR, 0.62; 95% CI, 0.41-0.94). The individual MACE outcomes were not significantly different between FFR-guided and angiography-guided CABG.

Conclusion

FFR-guided CABG might be beneficial in terms of the composite outcome of death or MI compared with angiography-guided CABG although data are limited.

The Role of Angiogenesis and Arteriogenesisin Myocardial Infarction and Coronary Revascularization

Surgical myocardial revascularization is associated with long-term survival benefit in patients with multivessel coronary artery disease. However, the exact biological mechanisms underlying the clinical benefits of myocardial revascularization have not been elucidated yet. Angiogenesis and arteriogenesis biologically leading to vascular collateralization are considered one of the endogenous mechanisms to preserve myocardial viability during ischemia, and the presence of coronary collateralization has been regarded as one of the predictors of long-term survival in patients with coronary artery disease (CAD). Some experimental studies and indirect clinical evidence on chronic CAD confirmed an angiogenetic response induced by myocardial revascularization and suggested that revascularization procedures could constitute an angiogenetic trigger per se. In this review, the clinical and basic science evidence regarding arteriogenesis and angiogenesis in both CAD and coronary revascularization is analyzed with the aim to better elucidate their significance in the clinical arena and potential therapeutic use.

What does complete revascularization mean in 2021? - Definitions, implications, and biases

PURPOSE OF REVIEW

Coronary revascularization is known to be an excellent treatment for coronary artery disease. However, whether incomplete myocardial revascularization compromises long-term outcomes, as compared to complete revascularization (CR), remains contentious. Herein, we review the concept of and evidence on CR/incomplete revascularization (ICR) and discuss future perspectives.

RECENT FINDINGS

When possible, achieving CR in coronary artery bypass grafting is desirable; nonetheless, ICR is also a reasonable option to balance the therapeutic benefits against the risks.

SUMMARY

Although angiography-based assessment currently remains the standard of care, fractional flow reserve guidance may reduce the number of lesions requiring revascularization, which may be helpful for an appropriate surgical revascularization strategy. In particular, utilizing this approach may refine hybrid revascularization procedures, especially among high-risk patients.

Fractional Flow Reserve-Based Coronary Artery Bypass Surgery: Current Evidence and Future Directions

Fractional flow reserve (FFR) provides an objective measurement of the severity of ischemia caused by coronary stenoses in downstream myocardial regions. Data from the interventional cardiology realm have suggested benefits of a FFR-guided percutaneous coronary intervention (PCI) strategy. Limited evidence is available on the use of FFR to guide coronary artery bypass grafting (CABG). The most recent data have shown that FFR might simplify CABG procedures and optimize patency of arterial grafts without any clear impact on clinical outcomes. The aim of this review was to summarize the available data on FFR-based CABG and discuss the rationale and potential consequences of a switch toward FFR-based surgical revascularization strategy.

Impacts of incomplete revascularization following off-pump coronary artery bypass grafting on clinical outcomes of patients with triple-vessel lesions: insights from a single-center study of propensity-matched data

Background

Although complete revascularization (CR) has been a goal of surgical revascularization, comorbidities and anatomical variables often conspire against a successful surgical CR. Currently, incomplete revascularization (IR) has been also considered as an acceptable strategy of surgical revascularization in some categories of patients. In the past decade, off-pump coronary artery bypass grafting (CABG) became one of the mainstream procedures of CABG due to its low incidence of perioperative complications. However, the magnitude of the impacts of off-pump IR on clinical outcomes of patients with triple-vessel disease remained unclear.

Methods

Eligible patients who received isolated off-pump CABG with left internal mammary artery (LIMA) grafting to the left anterior descending coronary artery (LAD) in our institute from January 2011 to December 2013 were entered into an IR group or a CR group. The incidence of off-pump IR was investigated. In-hospital and follow-up outcomes were also evaluated by adjusting baseline characteristics using propensity score matching (1:1).

Results

A total of 1,349 patients (268 in the IR group and 1,081 in the CR group) were analyzed. The off-pump IR rate was 19.9%. Using matching propensity scores, 234 pairs were successfully established in a 1:1 manner. The two matched groups had similar surgical mortality and major postoperative morbidity. Multivariate Cox regression analysis showed that IR was not an independent predictor of cardiac death at follow-up (HR =1.215; 95% CI, 0.883-2.164; P=0.371). The two matched groups received a similar cumulative survival freedom from repeat revascularization in Kaplan-Meier curves (χ²=2.120, log-rank P=0.145).

Conclusions

CR can be achieved in the majority of off-pump CABG cases. Compared with off-pump CR, off-pump IR with the LIMA grafting to the LAD was associated with acceptable clinical outcomes.

Is there a role for fractional flow reserve in coronary artery bypass graft (CABG) planning?

The concept of significant lesions has substantially evolved over the last decade. With growing evidence for use of fractional flow reserve (FFR) as a determinant of lesion-specific ischemia and its superiority to angiography-guided revascularization and medical therapy, the field of percutaneous revascularization has shifted to rely exclusively on FFR instead of luminal stenosis alone in guiding revascularization. This transition to physiological assessment has not yet made it to the realm of surgical revascularization. FFR-guided therapy has been shown to be superior to angiography-guided therapy mainly by safe deferral of about 1/3rd of lesions, leading to less periprocedural events and better outcomes. Is it possible that utilization of FFR-guided CABG would lead to less complicated procedures, shorter operating times, more frequent off pump CABG procedures and more hybrid procedures? Can FFR-guided CABG improve the cardiovascular outcomes as compared to current standard of practice? In the following paragraphs we review the concept of FFR, the evidence behind FFR-guided therapy, the emerging data regarding use FFR-guided CABG and discuss where the revascularization field is headed.

The Impact of Fractional Flow Reserve-Guided Coronary Revascularization in Patients with Coronary Stenoses of Intermediate Severity

BACKGROUND

Previous studies have shown that the use of fractional flow reserve (FFR) in addition to angiography significantly reduced the rate of all major adverse cardiovascular events (MACE). However, this practice has not been widely accepted and limited outcome data exist about FFR-guided percutaneous coronary intervention (PCI) in Taiwan. The aim of the present study was to evaluate the possible impact of FFR-guided PCI in coronary stenoses of intermediate severity.

METHODS

We performed a retrospective case-control study on 443 cases of intermediate coronary stenoses in 206 patients recruited from our computerized database. The study patients were divided into two groups: the FFR group (n = 101) and the angiography group (n = 105), matched with age, gender, clinical and angiographic lesion characteristics. In the angiography group, the indicated lesions had been treated with PCI by angiographic or anatomical assessment, whereas those patients in the FFR group underwent PCI of indicated lesions only if the FFR was < 0.80. The primary end point was the MACE rate regarding death, nonfatal myocardial infarction (MI), and target vessel failure at a mean follow-up of 418 days.

RESULTS

The MACE rate was similar in both groups (6% in the angiography group and 3% in the FFR group, p = 0.06). However, FFR-guided PCI strategy prevented unnecessary revascularization in up to 75% of patients, and markedly reduced costs of the index hospitalization. Moreover, multivariate analysis found that the use of drug-eluting stent and statin therapy, and the presence of family history of premature coronary artery disease and periprocedural MI are independent predictors of clinical outcomes.

CONCLUSIONS

FFR-guided intervention, compared to angiography-guided intervention for Taiwanese patients with coronary stenoses of intermediate severity, achieved similar clinical outcomes and provided cost-savings.

Is it time to change how we think about incomplete coronary revascularization?

The optimal degree of revascularization for patients with chronic multivessel coronary artery disease remains an unsolved issue. Intuitively, complete revascularization decreases cardiovascular events and improves outcomes compared to incomplete procedures, but in recent years the concept of incomplete revascularization moved from a sub-optimal or a defective treatment towards the most appropriate revascularization technique in some categories of patients. A reasonable level of incomplete anatomic revascularization has been shown to be safe and achievable with both percutaneous (PCI) and surgical procedures (CABG), despite with different long-term outcomes. What are the mechanisms underlying the clinical benefits of an incomplete revascularization and what are the factors explaining the discrepancy in the long-term clinical outcomes between the two modes of revascularization PCI and CABG? The biological consequences of coronary reperfusion might provide valuable hints in this context and at the same time cast new light on the way we think about incomplete revascularization.

Distinction of non-ischemia inducing versus ischemia inducing coronary stenosis by fluorescent cardiac imaging

Intraoperative fluorescent cardiac imaging (FCI) can quantitatively assess myocardial perfusion abnormalities produced by graded flow-limiting coronary stenosis (FLS), but there are no data to distinguish FLS from non flow-limiting stenosis (NFLS) to determine their functional significance. The aim of the study was to evaluate whether non-ischemia inducing NFLS can be quantified and differentiated from FLS by FCI technology. Data are compared to gold standard fluorescent microspheres (FM). 11 domestic pigs of either sex underwent sternotomy. Left anterior descending coronary artery blood-flow was recorded by transit-time flow measurements. After baseline and Adenosine-induced hyperemia, two stenosis of low severity (50 and 90 % NFLS) were produced, followed by FLS (50 %) and total vessel occlusion. Time-dependent fluorescence intensity curves were recorded by FCI. Slope of fluorescence intensity (SFI) and background-subtracted peak fluorescence (BSFI) intensity were calculated and data compared to myocardial blood flow measurements using FM. All NFLS and FLS reduced myocardial perfusion as quantified by FCI showing decreased normalized BSFI and SFI (P < 0.001). Box-plot analysis showed significant difference between NFLS (50 and 90 %) and FLS (50 %) assessed by BSFI (P < 0.001) and SFI (P < 0.001). In each animal, a linear correlation between FM-derived myocardial blood flow and FCI-derived BSFI (r = 0.936, P < 0.001) or SFI (r = 0.942, P < 0.001) was observed during baseline, hyperemia, graded NFLS, and FLS. Both, BSFI (r = 0.789, P < 0.001) and SFI (r = 0.802, P < 0.001) significantly correlated with transit-time flow measurements. FCI quantitative technology is capable of distinguishing between non-ischemia inducing NFLS and ischemia inducing FLS showing a good correlation compared to fluorescent microspheres.